CVE-2016-9596 in JBoss
Summary
by MITRE
libxml2, as used in Red Hat JBoss Core Services and when in recovery mode, allows context-dependent attackers to cause a denial of service (stack consumption) via a crafted XML document. NOTE: this vulnerability exists because of an incorrect fix for CVE-2016-3627.
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Analysis
by VulDB Data Team • 03/16/2020
The vulnerability identified as CVE-2016-9596 represents a critical denial of service weakness within libxml2 library versions used in Red Hat JBoss Core Services, particularly when operating in recovery mode. This issue stems from an improper remediation approach to a previously discovered vulnerability, creating a recurring security flaw that attackers can exploit through carefully constructed XML documents. The vulnerability manifests when the XML parser processes malformed input that triggers excessive stack memory consumption, ultimately leading to system resource exhaustion and service disruption.
The technical root cause of CVE-2016-9596 lies in the libxml2 library's inadequate handling of recursive XML structures during parsing operations. When the library encounters specially crafted XML documents that contain deeply nested elements or circular references, the parsing algorithm consumes excessive stack space proportional to the document complexity. This behavior aligns with CWE-772, which addresses Missing Release of Resource after Effective Lifetime, specifically in the context of stack memory consumption. The vulnerability demonstrates characteristics of CWE-400, Uncontrolled Resource Consumption, as the parser fails to implement proper recursion depth limits or stack usage monitoring during XML processing.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the availability of critical business applications running on JBoss platforms. Attackers can leverage this weakness to consume system resources rapidly through carefully crafted XML requests, leading to denial of service conditions that may affect multiple concurrent users or processes. The recovery mode aspect of the vulnerability is particularly concerning as it suggests that even when systems are attempting to recover from previous failures, they remain susceptible to resource exhaustion attacks. This vulnerability affects organizations using Red Hat JBoss Core Services, where XML processing is a fundamental component of many enterprise applications, making it a significant concern for financial services, healthcare, and government sectors that rely on these platforms.
Mitigation strategies for CVE-2016-9596 require immediate implementation of updated libxml2 versions that properly address the recursion handling issues without introducing regressions. Organizations should implement XML input validation and size limits to prevent processing of excessively large or complex documents. Network-level protections such as XML firewall rules and rate limiting can help reduce the impact of exploitation attempts. Security teams should also monitor system resources for unusual stack consumption patterns and implement proper logging of XML processing activities to detect potential exploitation attempts. The remediation process must include thorough regression testing to ensure that the updated library does not break existing functionality while addressing the stack consumption vulnerability. This vulnerability underscores the importance of proper vulnerability management and the risks associated with inadequate patching approaches that may introduce new security weaknesses rather than resolving existing ones.